1. Field of the Invention
The present invention relates to a local multipoint distribution system (LMDS)and more particularly to a LMDS and method of communicating asynchronous transfer mode (ATM) data.
2. Background of the Related Art
A LMDS is a broadband wireless network which provides high speed broadband multimedia service to subscribers using a millimeter band frequency for customer circuits. LMDSs have been developed to efficiently distribute cable television channels, and has gradually evolved to bidirectional digital communication systems. The LMDS can provide various services such as voice telephone service, data communication service, multimedia service processing with audio, video, and data information, or exclusive lines service. The LMDS has advantages over general networks of wire communication systems in view of easiness, extensional, and economical efficiency.
Presently, numerous countries are developing wireless network services with their own project names. For example, the USA is developing Local Multipoint Distribution Systems (LMDS), Canada is developing Local Multipoint Communication Systems (LMCS), Japan is developing ATM Wireless Access (AWA) systems, and Korea is developing Broadband Wireless Local Loop (B-WLL) systems, respectively.
The Digital Audio Visual Council (DAVIC) has proposed standardization for wireless network services, such as for LMDS, which was published from version 1.1 to version 1.3 of their proposals. The suggested proposals were for Downstream Time Division Multiplexing, Upstream Time Division Multiple Access (MA), downstream or upstream frame structure, and Medium Access Control (MAC) Protocol, etc. The LMDS includes a service provider and customer premises equipment units (CPE) for performing wireless communication with the service provider. The service provider includes a central office unit(COU) for transmitting a digital data stream received from a program provider, a head-end unit for receiving downstream data from the CPE, for modulating and transmitting the downstream data, and for demodulating and transmitting a received upstream data from a base station to the CPE. The service provider also includes a hub outdoor unit for amplifying the downstream data and performing frequency conversion for transmission to corresponding CPEs via a antenna, amplifying the upstream data, and performing frequency conversion for transmission to the head-end unit.
However, each inner block of LMDS structure was not disclosed in detail, in the proposals, due to a policy of protecting the technology developed by each country. Specifically, any specifications for system developers and proposal for ATM signal treatment over a LMDS was not suggested in the latest DAVIC version. Accordingly, an improved LMDS is needed which can be easily embodied to allow ATM signal treatment work with developed or developing LMDSs.